Hello, @파랑머리. Apologies for replying in English - I don’t speak Korean.
I understand that you’re looking to cancel your Professional subscription and get a refund; since we can’t assist directly with billing and account issues like that here in the forum, I created a ticket for you with our customer support team. You should get that shortly via email. In the meantime, if you’re looking to cancel your service then what you want to do is remove the seats you have assigned to team members. This is covered in our support article on managing billing on the Professional plan, and in specific you will want to do the following:
From the file browser, click Admin in the left sidebar.
Select the People tab.
Click a person’s current seat from the Seat type column.
In the popup modal, select the free View seat and confirm the changes.
Let me know if you have any other questions - happy to help!